Abstract
This study examines the performance of a GaN HEMT with a 150 nm gate length, fabricated on silicon carbide, across various operational modes, including direct current (DC), radio frequency (RF), and small-signal parameters. The evaluation of DC, RF, and small-signal performance under diverse bias conditions remains a relatively unexplored area of study for this specific technology. The DC characteristics revealed relatively little I(ds) at zero gate and drain voltages, and the current grew as V(gs) increased. Essential measurements include I(dss) at 109 mA and I(dssm) at 26 mA, while the peak g(m) was 62 mS. Because transconductance is sensitive to variations in V(gs) and V(ds), it shows "Vth (roll-off)," where Vth decreases as V(ds) increases. The transfer characteristics corroborated this trend, illustrating the impact of drain-induced barrier lowering (DIBL) on threshold voltage (Vth) values, which spanned from -5.06 V to -5.71 V across varying drain-source voltages (V(ds)). The equivalent-circuit technique revealed substantial non-linear behaviors in capacitances such as C(gs) and C(gd) concerning V(gs) and V(ds), while also identifying extrinsic factors including parasitic capacitances and resistances. Series resistances (R(gs) and R(gd)) decreased as V(gs) increased, thereby enhancing device conductivity. As V(gs) approached neutrality, particularly at elevated V(ds) levels, the intrinsic transconductance (g(mo)) and time constants (τ(gm), τ(gs), and τ(gd)) exhibited enhanced performance. f(t) and f(max), which are essential for high-frequency applications, rose with decreasing V(gs) and increasing V(ds). When V(gs) approached -3 V, the S(21) and Y(21) readings demonstrated improved signal transmission, with peak S(21) values of approximately 11.2 dB. The stability factor (K), which increased with V(ds), highlighted the device's operational limits. The robust correlation between simulation and experimental data validated the equivalent-circuit model, which is essential for enhancing design and creating RF circuits. Further examination of bias conditions would enhance understanding of the device's performance.